I have a large wireless ISP network that I have been given the opportunity to re-design due to selling the existing ISP business, although there are a handful of large business customers we are keeping. I was initially wanting to place managed switches at each tower and trunk everything back to the core router. However, in recent months I have been reading where more and more, layer 3 switches are being placed in closets and pushing routing functions out to the individual closets, or in this case, towers. Therein lies my question. My new design is beginning to resemble this last method by placing CRS-125s at each tower, and placing IP subnets on each port used, thereby routing everything back to the core rather than layer 2 trunking. We have several businesses that have multiple locations, and this design makes sense to me from the standpoint of their traffic isn’t bound for the internet, it is bound for one of their locations off a different tower, and therefore, through the use of OSPF at each tower, I could feasibly keep traffic more localized rather than setting up trunk links and putting a VLAN on each tower.
Anybody else see a problem with this theory/methodology/design/whatever?
I would look closely at the CRS-125 series’ current “layer 3 switch” performance before assuming that it is better than a traditional router for a given task. There seem to have been several posts from people whose assumptions about the CRS had not held up.
Running OSPF at each tower may well make sense and if you have several businesses with multiple locations I would suggest that you seriously think about implementing MPLS/VPLS capabilities on the redesigned network.
I didn’t even think about mpls as a feature of my design. thank you for pointing that out. As for crs125 performance I was mainly considering using the routing capabilities not necessarily the switching features, but if you have a suggestion on better equipment I am open. I don’t think Cisco will be an option due to cost though.